Electronic devices with integrated circuit chips encapsulated in plastic packaging have been employed for some years. Typically, an epoxy resin is molded around the chip, a central portion of a lead frame and bonding wires or other connections between contact pads on the chip to inner lead fingers on the lead frame. It is sometimes necessary to decapsulate such as plastic-encapsulated package at least in part to allow for inspection, test and repair of the chip or the wire bonds to the chip, or the inner lead fingers, after the epoxy covering these elements is safely and effectively removed. In general, concentrated acids such as sulfuric and nitric acids or other solvents for the resin have been used in a decapsulation system for removing plastic material to expose the encapsulated chip or package elements.
U.S. Pat. No. 5,766,496 describes a decapsulation system for selectively etching an encapsulant of a plastic-encapsulated package. U.S. Pat. No. 6,350,110 B1 describes a multi-port metering pump which can be incorporated in a decapsulation system to deliver a very small volume of liquid to the etch head. A suitable decapsulation system should be capable of providing control of the amount of etching, preventing damage to the chip or package elements, and providing safety of use.